US20260019058A1 - Filter device and method for controlling a filter device - Google Patents

Filter device and method for controlling a filter device

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Publication number
US20260019058A1
US20260019058A1 US19/332,135 US202519332135A US2026019058A1 US 20260019058 A1 US20260019058 A1 US 20260019058A1 US 202519332135 A US202519332135 A US 202519332135A US 2026019058 A1 US2026019058 A1 US 2026019058A1
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United States
Prior art keywords
capacitor
inductor
terminal
filter device
resonator
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Pending
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US19/332,135
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English (en)
Inventor
Naoki Mizoguchi
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Murata Manufacturing Co Ltd
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Murata Manufacturing Co Ltd
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Publication of US20260019058A1 publication Critical patent/US20260019058A1/en
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H7/00—Multiple-port networks comprising only passive electrical elements as network components
    • H03H7/01—Frequency selective two-port networks
    • H03H7/0153—Electrical filters; Controlling thereof
    • H03H7/0161—Bandpass filters
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H1/00—Constructional details of impedance networks whose electrical mode of operation is not specified or applicable to more than one type of network
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H7/00—Multiple-port networks comprising only passive electrical elements as network components
    • H03H7/01—Frequency selective two-port networks
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H7/00—Multiple-port networks comprising only passive electrical elements as network components
    • H03H7/01—Frequency selective two-port networks
    • H03H7/0115—Frequency selective two-port networks comprising only inductors and capacitors
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H7/00—Multiple-port networks comprising only passive electrical elements as network components
    • H03H7/01—Frequency selective two-port networks
    • H03H7/09—Filters comprising mutual inductance
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H7/00—Multiple-port networks comprising only passive electrical elements as network components
    • H03H7/01—Frequency selective two-port networks
    • H03H7/17—Structural details of sub-circuits of frequency selective networks
    • H03H7/1708—Comprising bridging elements, i.e. elements in a series path without own reference to ground and spanning branching nodes of another series path
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H7/00—Multiple-port networks comprising only passive electrical elements as network components
    • H03H7/01—Frequency selective two-port networks
    • H03H7/17—Structural details of sub-circuits of frequency selective networks
    • H03H7/1741—Comprising typical LC combinations, irrespective of presence and location of additional resistors
    • H03H7/1766—Parallel LC in series path
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H7/00—Multiple-port networks comprising only passive electrical elements as network components
    • H03H7/01—Frequency selective two-port networks
    • H03H7/17—Structural details of sub-circuits of frequency selective networks
    • H03H7/1741—Comprising typical LC combinations, irrespective of presence and location of additional resistors
    • H03H7/1775—Parallel LC in shunt or branch path
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H1/00—Constructional details of impedance networks whose electrical mode of operation is not specified or applicable to more than one type of network
    • H03H2001/0021—Constructional details
    • H03H2001/0085—Multilayer, e.g. LTCC, HTCC, green sheets

Definitions

  • Patent Document 1 discloses a low pass filter as an example of a multilayer electronic component.
  • the low pass filter according to Patent Document 1 at least some of a plurality of ground side electrodes disposed on a side surface of a multilayer body are not connected to an insulating substrate, to thereby control the frequency of an attenuation pole generated by a parasitic inductor.
  • the present disclosure has been made to address the above issue, and is directed to preventing or reducing a deterioration in attenuation characteristics due to spurious generated in a filter device.
  • An aspect of the present disclosure provides a filter device including an input terminal, an output terminal, a ground terminal, and a first resonator connected to the input terminal and the output terminal.
  • the first resonator includes a first terminal connected to the input terminal, a second terminal connected to the output terminal, first and second inductors, and first to third capacitors.
  • One end of the first inductor is connected to the first terminal.
  • One end of the second inductor is connected to the second terminal, and the other end thereof is connected to the other end of the first inductor.
  • One end of the first capacitor is connected to the first terminal.
  • One end of the second capacitor is connected to the second terminal, and the other end thereof is connected to the other end of the first capacitor.
  • the third capacitor is connected between the other end of the first inductor and the other end of the first capacitor.
  • a filter device including a multilayer body in which a plurality of dielectrics are stacked, an input terminal, an output terminal, a ground terminal, first and second paths, and first to fourth capacitor electrodes.
  • the first path is connected to the input terminal.
  • the second path is connected to the output terminal.
  • the first capacitor electrode is connected to the first path.
  • the second capacitor electrode is connected to the second path.
  • the third capacitor electrode is connected to the first and second paths.
  • a capacitor (third capacitor) for spurious adjustment is disposed between an intermediate portion of the inductors and an intermediate portion of the capacitors of the resonator.
  • FIG. 1 is an equivalent circuit diagram of a filter device according to a first embodiment.
  • FIG. 2 is a perspective view of an outer shape of the filter device according to the first embodiment.
  • FIG. 3 is an exploded perspective view illustrating an example of a multilayer structure of the filter device in FIG. 2 .
  • FIG. 4 is an equivalent circuit diagram of a filter device according to a comparative example.
  • FIG. 5 illustrates filter characteristics of the filter devices according to the first embodiment and the comparative example.
  • FIG. 6 is a first diagram for explaining the reason for generation of spurious.
  • FIG. 7 is a second diagram for explaining the reason for the generation of spurious.
  • FIG. 8 illustrates the filter characteristics for a case where line lengths of inductors of a resonator are adjusted.
  • FIG. 9 is an equivalent circuit diagram of a filter device according to a first modification.
  • FIG. 10 is an equivalent circuit diagram of a filter device according to a second modification.
  • FIG. 11 is an equivalent circuit diagram of a filter device according to a second embodiment.
  • FIG. 12 is an exploded perspective view illustrating an example of a multilayer structure of the filter device according to the second embodiment.
  • FIG. 13 is a first diagram for explaining the reason that a level of spurious is adjustable.
  • FIG. 14 is a second diagram for explaining the reason that the level of spurious is adjustable.
  • FIG. 15 illustrates filter characteristics of the filter device according to the second embodiment.
  • FIG. 16 is an equivalent circuit diagram of a filter device according to a third modification.
  • FIG. 17 is an equivalent circuit diagram of a filter device according to a fourth modification.
  • FIG. 18 is an equivalent circuit diagram of a filter device according to a fifth modification.
  • FIG. 19 is an equivalent circuit diagram of a filter device according to a third embodiment.
  • FIG. 20 illustrates filter characteristics of the filter device according to the third embodiment.
  • FIG. 21 is an equivalent circuit diagram of a filter device according to a fourth embodiment.
  • FIG. 22 illustrates filter characteristics of the filter device according to the fourth embodiment.
  • FIG. 23 is an equivalent circuit diagram of a filter device according to a sixth modification.
  • FIG. 24 illustrates filter characteristics of the filter device according to the sixth modification.
  • FIG. 1 is an equivalent circuit diagram of a filter device 100 according to a first embodiment.
  • the filter device 100 includes an input terminal T 1 , an output terminal T 2 , a ground terminal GND, resonators RC 0 and RC 1 , capacitors C 1 and C 2 , and an inductor L 31 .
  • the resonator RC 0 includes an inductor L 11 and a capacitor C 11 .
  • the resonator RC 1 includes capacitors C 21 to C 23 and inductors L 21 and L 22 .
  • the resonator RC 0 is connected to the input terminal T 1 . More specifically, one end of the inductor L 11 is connected to the input terminal T 1 , and the capacitor C 11 is connected in parallel with the inductor L 11 .
  • One end of the inductor L 31 is connected to the output terminal T 2 .
  • a terminal N 1 (first terminal) of the resonator RC 1 is connected to the other end of the inductor L 11 included in the resonator RC 0
  • a terminal N 2 (second terminal) of the resonator RC 1 is connected to the other end of the inductor L 31 .
  • the inductors L 21 and L 22 connected in series are connected between the terminal N 1 connected to the inductor L 11 and the terminal N 2 connected to the inductor L 31 .
  • One end of the capacitor C 21 is connected to the terminal N 1 , and the other end thereof is connected to one end of the capacitor C 22 .
  • the other end of the capacitor C 22 is connected to the terminal N 2 . That is, the capacitors C 21 and C 22 connected in series are connected in parallel with the inductors L 21 and L 22 connected in series.
  • the capacitor C 23 is connected between a first connection node N 11 between the inductor L 21 and the inductor L 22 and a second connection node N 12 between the capacitor C 21 and the capacitor C 22 .
  • the capacitor C 1 is connected between the terminal N 1 of the resonator RC 1 and the ground terminal GND.
  • the capacitor C 2 is connected between the terminal N 2 of the resonator RC 1 and the ground terminal GND. That is, the filter device 100 constitutes a so-called fifth-order low pass filter.
  • connection means not only a case where two elements are directly connected but also a case where two elements are connected via another element.
  • FIG. 2 is a perspective view of an outer shape of the filter device 100
  • FIG. 3 is an exploded perspective view illustrating an example of a multilayer structure of the filter device 100 .
  • the filter device 100 includes a multilayer body 110 of a rectangular parallelepiped or a substantially rectangular parallelepiped in which a plurality of dielectric layers LY 1 to LY 14 are stacked in the stacking direction.
  • the dielectric layers LY 1 to LY 14 are formed of a ceramic such as low-temperature co-fired ceramics (LTCC) or a resin, for example.
  • the inductors and the capacitors illustrated in FIG. 1 are constituted by a plurality of electrodes provided in the dielectric layers and a plurality of vias provided between the dielectric layers inside the multilayer body 110 .
  • the term “via” as used herein refers to a columnar conductor provided in a dielectric layer to connect electrodes provided in different dielectric layers.
  • the via is formed by conductive paste, plating, and/or a metal pin, for example.
  • the stacking direction of the dielectric layers LY 1 to LY 14 in the multilayer body 110 is defined as a “Z-axis direction”
  • the direction perpendicular to the Z-axis direction and along the long sides of the multilayer body 110 is defined as an “X-axis direction”
  • the direction along the short sides of the multilayer body 110 is defined as a “Y-axis direction”.
  • the positive direction and the negative direction of the Z-axis in the drawings are occasionally referred to as an upper side and a lower side, respectively.
  • a direction mark DM for specifying the direction of the filter device 100 is disposed on an upper surface 111 (dielectric layer LY 1 ) of the multilayer body 110 .
  • External terminals (input terminal T 1 , output terminal T 2 , and ground terminal GND) for connecting the filter device 100 to an external device are disposed on a lower surface 112 (dielectric layer LY 14 ) of the multilayer body 110 .
  • the input terminal T 1 , the output terminal T 2 , and the ground terminal GND are each a flat plate electrode having a substantially rectangular shape, and are land grid array (LGA) terminals disposed regularly on the lower surface 112 of the multilayer body 110 .
  • LGA land grid array
  • the input terminal T 1 is disposed along the short side of the lower surface 112 in the positive direction of the X-axis.
  • the output terminal T 2 is disposed along the short side of the lower surface 112 in the negative direction of the X-axis.
  • the ground terminal GND is disposed between the input terminal T 1 and the output terminal T 2 in the X-axis direction.
  • the input terminal T 1 is connected to a flat plate electrode P 1 disposed in the dielectric layer LY 13 by a via V 10 .
  • the flat plate electrode P 1 is an electrode having a substantially L-shape when viewed in plan view from the stacking direction (Z-axis direction).
  • the flat plate electrode P 1 is connected to a capacitor electrode PC 10 disposed in the dielectric layer LY 9 , a capacitor electrode PC 11 disposed in the dielectric layer LY 7 , and a flat plate electrode PL 10 disposed in the dielectric layer LY 2 by a via V 11 .
  • the flat plate electrode PL 10 disposed in the dielectric layer LY 2 is an electrode in a linear band shape extending in the Y-axis direction.
  • the via V 11 is connected to a first end portion of the flat plate electrode PL 10
  • a via V 12 is connected to a second end portion thereof.
  • the via V 12 is connected to a flat plate electrode PL 11 disposed in the dielectric layer LY 4 .
  • the flat plate electrode PL 11 is an electrode having a substantially L-shape when viewed in plan view from the stacking direction.
  • the via V 12 is connected to a first end portion of the flat plate electrode PL 11 , and a via V 13 is connected to a second end portion thereof.
  • the via V 13 is connected to a flat plate electrode PL 20 disposed in the dielectric layer LY 2 .
  • the via V 13 is also connected to a capacitor electrode PC 22 disposed in the dielectric layer LY 7 , a capacitor electrode PC 12 disposed in the dielectric layer LY 8 , and a capacitor electrode PC 3 disposed in the dielectric layer LY 9 .
  • the flat plate electrode PL 20 is an electrode having a substantially L-shape when viewed in plan view from the stacking direction.
  • the via V 13 is connected to a first end portion of the flat plate electrode PL 20 , and a via V 20 is connected to a second end portion thereof.
  • the via V 20 is connected to a capacitor electrode PC 20 disposed in the dielectric layer LY 5 .
  • a via V 21 is also connected to the capacitor electrode PC 20 .
  • the via V 21 is connected to a flat plate electrode PL 30 disposed in the dielectric layer LY 2 .
  • the capacitor electrode PC 4 is connected to a capacitor electrode PC 2 disposed in the dielectric layer LY 11 via a via V 23 .
  • a capacitor electrode PC 2 disposed in the dielectric layer LY 11 via a via V 23 .
  • the capacitor C 2 in FIG. 1 is constituted by the capacitor electrode PC 2 and the ground electrode PG 1 .
  • the capacitor C 21 in FIG. 1 is constituted by the capacitor electrodes PC 21 and PC 24 and the capacitor electrodes PC 22 and PC 3 .
  • the capacitor C 22 in FIG. 1 is constituted by the capacitor electrodes PC 21 and PC 24 and the capacitor electrodes PC 23 and PC 4 .
  • the capacitor C 23 in FIG. 1 is constituted by the capacitor electrode PC 20 and the capacitor electrode PC 21 .
  • FIG. 4 is an equivalent circuit diagram of a filter device 100 X according to a comparative example.
  • the resonator RC 1 in the filter device 100 has been replaced with a resonator RC 1 X.
  • the resonator RC 1 X has a configuration in which an inductor L 21 X and a capacitor C 21 X are connected in parallel.
  • the filter device 100 X corresponds to the configuration of the filter device 100 according to the first embodiment from which the capacitor C 23 of the resonator RC 1 has been removed.
  • a frequency band BW 1 of a signal targeted by the filter device 100 according to the first embodiment is the range of the microwave bands of 0 to 6 GHz, for example, and a frequency band BW 2 of another signal in the communication device is the range of the millimeter wave bands of 27.5 GHZ to 40 GHZ.
  • a good insertion loss is obtained in the frequency band BW 1 of microwaves, as indicated by the line LN 18 in the right part.
  • spurious is generated around 33 GHz in the frequency band BW 2 of millimeter waves, and the attenuation decreases and the attenuation characteristics deteriorate at the spurious portion.
  • the inductance value of the inductor L 21 X in the resonator RC 1 X is defined as L 0
  • the capacitance value of the capacitor C 21 X therein is defined as C 0
  • the inductance values of the inductors L 21 and L 22 in the resonator RC 1 are defined as L 01 and L 02 , respectively
  • the capacitance values of the capacitors C 21 to C 23 are defined as C 01 , C 02 , and Ca, respectively.
  • a frequency fs of the spurious varies. Specifically, as the stray capacitance Ca becomes larger, the frequency fs of the spurious becomes gradually lower in the order of fs 3 , fs 2 , and fs 1 toward F 0 .
  • the resonant frequency F 0 of the entire resonator does not substantially vary even if the stray capacitance Ca varies.
  • the frequency at which spurious is generated can be intentionally adjusted by disposing a capacitor between an intermediate portion of the inductors and an intermediate portion of the capacitors of the resonator. Further, in the resonator, the level of spurious can be reduced by adjusting the lengths of two inductors connected to the capacitor for spurious adjustment and adjusting the resonant frequencies F 1 and F 2 of resonators formed on the input side and the output side of the capacitor to approximately the same degree.
  • the “resonator RC 1 ” according to the first embodiment corresponds to the “first resonator” according to the present disclosure.
  • the “inductor L 21 ”, “inductor L 22 ”, “inductor L 11 ”, and “inductor L 31 ” according to the first embodiment correspond to the “first inductor” to “fourth inductor”, respectively, according to the present disclosure.
  • the “capacitor C 21 ”, “capacitor C 22 ”, and “capacitor C 23 ” according to the first embodiment correspond to the “first capacitor” to “third capacitor”, respectively, according to the present disclosure.
  • the “capacitor C 1 ” and “capacitor C 2 ” according to the first embodiment correspond to the “fifth capacitor” and “sixth capacitor”, respectively, according to the present disclosure.
  • the “capacitor C 11 ” according to the first embodiment corresponds to the “seventh capacitor” according to the present disclosure.
  • the “frequency band BW 1 ” and “frequency band BW 2 ” according to the first embodiment correspond to the “first frequency band” and “second frequency band”, respectively, according to the present disclosure.
  • capacitor electrode PC 22 corresponds to the “first capacitor electrode” to “fourth capacitor electrode”, respectively, according to the present disclosure.
  • a capacitor for spurious adjustment is disposed between an intermediate portion of the inductors and an intermediate portion of the capacitors of the LC parallel resonator.
  • the frequency of spurious is adjusted by disposing an LC series resonator between an intermediate portion of the inductors and an intermediate portion of the capacitors of the LC parallel resonator.
  • FIG. 9 is an equivalent circuit diagram of a filter device 100 A according to a first modification.
  • an inductor L 23 is added to a portion of the capacitor C 23 in the configuration of the filter device 100 illustrated in FIG. 1 . More specifically, the inductor L 23 is disposed between the first connection node N 11 between the inductor L 21 and the inductor L 22 and the capacitor C 23 .
  • the configuration in FIG. 9 is otherwise the same as that in FIG. 1 , and elements that are the same as those in FIG. 1 will not be described.
  • the frequency of spurious to be generated can be adjusted by adjusting the resonant frequency of the LC series resonator.
  • the capacitance of the capacitor needed for a frequency adjustment circuit can be reduced by using the LC series resonator instead of using only the capacitor, which makes it possible to reduce the device size.
  • the arrangement of the inductor L 23 and the capacitor C 23 may be reversed. That is, the capacitor C 23 may be connected to the first connection node N 11 , and the inductor L 23 may be connected between the capacitor C 23 and the second connection node N 12 .
  • the filter device is a fifth-order low pass filter in the first embodiment and the first modification, the features of the present disclosure are also applicable to a third-order low pass filter.
  • FIG. 10 is an equivalent circuit diagram of a filter device 100 B according to a second modification.
  • the filter device 100 B the resonator RC 0 and the inductor L 31 have been removed from the filter device 100 illustrated in FIG. 1 . That is, the filter device 100 B is a third-order low pass filter composed of the resonator RC 1 and the capacitors C 1 and C 2 which are shunt capacitors.
  • a circuit that reduces the level of spurious is added to the configuration according to the first embodiment.
  • the capacitor C 25 is disposed between the first connection node N 11 between the inductor L 21 and the inductor L 22 and the ground terminal GND.
  • the potential of the capacitor C 23 for spurious adjustment relative to the ground potential can be specified by the capacitor C 25 .
  • the anti-resonant frequency and the resonant frequency of spurious can be brought closer by adjusting the magnitude of the capacitor C 25 after adjusting the frequency of spurious using the capacitor C 23 , which makes it possible to reduce the level of spurious through the cancellation of an anti-resonant point and a resonant point.
  • FIG. 12 is an exploded perspective view illustrating an example of a multilayer structure of the filter device 100 C according to the second embodiment.
  • the vias V 20 and V 21 in the exploded perspective view of the filter device 100 illustrated in FIG. 3 have been replaced with vias V 20 C and V 21 C, respectively.
  • capacitor electrodes PC 25 and PC 26 are connected to end portions of the vias V 20 C and V 21 C, respectively.
  • the via V 20 C is connected not only to the flat plate electrode PL 20 in the dielectric layer LY 2 and the capacitor electrode PC 20 in the dielectric layer LY 5 , but also to the capacitor electrode PC 25 disposed in the dielectric layer LY 10 .
  • the via V 21 C is connected not only to the flat plate electrode PL 30 in the dielectric layer LY 2 and the capacitor electrode PC 20 in the dielectric layer LY 5 , but also to the capacitor electrode PC 26 disposed in the dielectric layer LY 10 .
  • the capacitor electrodes PC 25 and PC 26 are each an electrode in a band shape extending in the X-axis direction, and at least a part of each of the capacitor electrodes PC 25 and PC 26 is superposed on the ground electrode PG 1 in the dielectric layer LY 12 when viewed in plan view from the stacking direction. That is, the capacitor C 25 in FIG. 11 is constituted by the capacitor electrodes PC 25 and PC 26 and the ground electrode PG 1 .
  • FIG. 13 illustrates a portion of the resonator RC 1 and the capacitors C 1 and C 2 , in the filter device 100 C illustrated in FIG. 11 .
  • FIG. 13 illustrates a low pass filter obtained by removing the resonator RC 0 and the inductor L 31 from the filter device 100 C.
  • FIG. 14 indicates results of simulating the insertion loss (solid lines LN 81 , LN 83 , and LN 85 ) and the return loss (broken lines LN 82 , LN 84 , and LN 86 ) at the time when a capacitance value Cb of the capacitor C 25 is varied in the filter in FIG. 13 .
  • the center part of FIG. 14 indicates a case where the capacitance value Cb of the capacitor C 25 is in the vicinity of a specific capacitance value Copt (Cb ⁇ Copt).
  • the left part indicates a case where the capacitance value Cb is larger than the capacitance value Copt (Cb>Copt), and the right part indicates a case where the capacitance value Cb is smaller than the capacitance value Copt (Cb ⁇ Copt).
  • the level of spurious is low when the capacitance value Cb of the capacitor C 25 is approximately the same as the capacitance value Copt.
  • the capacitance value Cb is larger than the capacitance value Copt (left part)
  • a resonant point is generated on the lower frequency side than the frequency fs at which spurious is generated, and an anti-resonant point is generated on the higher frequency side than the frequency fs at which spurious is generated.
  • the capacitance value Copt is a capacitance value for a case where a resonant point and an anti-resonant point at which spurious is generated coincide with each other. Consequently, the amplitude at the anti-resonant point which hinders attenuation is canceled out by the amplitude at the resonant point, which reduces the level of spurious.
  • the resonant frequency F 0 of the entire filter and the frequency fs of spurious do not substantially vary even when the capacitance value Cb is varied. That is, the level of spurious can be adjusted, while the effects on the resonant frequency F 0 of the filter device and the frequency fs of spurious are prevented or reduced, by varying the capacitance value Cb of the capacitor C 25 .
  • FIG. 15 illustrates filter characteristics of the filter device 100 C according to the second embodiment.
  • a solid line LN 30 indicates the insertion loss
  • a broken line LN 35 indicates the return loss.
  • the capacitance value of the capacitor C 25 has an optimum value Copt for the configuration of the filter device, and the level of spurious increases when the capacitance value is larger or smaller than the optimum value.
  • the capacitance value is larger than the optimum value, a resonant point and an anti-resonant point of spurious appear in this order from the low frequency side toward the high frequency side.
  • the capacitance value is smaller than the optimum value, conversely, an anti-resonant point and a resonant point of spurious appear in this order from the low frequency side toward the high frequency side.
  • the level of spurious to be generated can be reduced by adding a capacitor between the capacitor for adjusting the frequency of spurious and the ground terminal and adjusting the capacitance value of the capacitor.
  • the “capacitor C 25 ” according to the second embodiment corresponds to an example of the “fourth capacitor” according to the present disclosure.
  • the “capacitor electrode PC 25 ” and “capacitor electrode PC 26 ” according to the second embodiment correspond to the “fifth capacitor electrode” and “sixth capacitor electrode”, respectively, according to the present disclosure.
  • a capacitor is added between the electrode, on the side of the inductors L 21 and L 22 , of the capacitor C 23 for adjusting the frequency of spurious and the ground terminal GND.
  • a capacitor is added between the electrode, on the side of the capacitors C 21 and C 22 , of the capacitor C 23 and the ground terminal GND.
  • FIG. 16 is an equivalent circuit diagram of a filter device 100 D according to a third modification.
  • a capacitor C 26 is added between the capacitor C 23 in the resonator RC 1 of the filter device 100 and the ground terminal GND. More specifically, the capacitor C 26 is disposed between the second connection node N 12 between the capacitor C 21 and the capacitor C 22 and the ground terminal GND.
  • the potential of the capacitor C 23 for spurious adjustment relative to the ground potential can be specified. Further, the anti-resonant frequency and the resonant frequency of spurious can be brought closer by adjusting the magnitude of the capacitor C 26 after adjusting the frequency of spurious using the capacitor C 23 , which makes it possible to reduce the level of spurious through the cancellation of an anti-resonant point and a resonant point.
  • the “capacitor C 26 ” according to the third modification corresponds to an example of the “fourth capacitor” according to the present disclosure.
  • an LC series resonator is disposed at a portion of the shunt capacitor for adjusting the level of spurious in the configuration according to the second embodiment.
  • FIG. 17 is an equivalent circuit diagram of a filter device 100 E according to a fourth modification.
  • an inductor L 25 is added to the filter device 100 C according to the second embodiment illustrated in FIG. 11 . More specifically, the inductor L 25 is disposed between the capacitor C 25 and the ground terminal GND.
  • An LC series resonator is constituted by the capacitor C 25 and the inductor L 25 .
  • connection of the inductor L 25 and the capacitor C 25 in the LC series resonator may be reversed.
  • an LC series resonator is disposed at a portion of the shunt capacitor for adjusting the level of spurious in the configuration according to the third modification.
  • FIG. 18 is an equivalent circuit diagram of a filter device 100 F according to a fifth modification.
  • an inductor L 26 is added to the filter device 100 D according to the third modification illustrated in FIG. 16 . More specifically, the inductor L 26 is disposed between the capacitor C 26 and the ground terminal GND.
  • An LC series resonator is constituted by the capacitor C 26 and the inductor L 26 .
  • the anti-resonant frequency and the resonant frequency of spurious can be brought closer by disposing an LC series resonator between the capacitor for adjusting the frequency of spurious and the ground terminal GND. Consequently, it is possible to reduce the level of spurious through the cancellation of an anti-resonant point and a resonant point.
  • connection of the inductor L 26 and the capacitor C 26 in the LC series resonator may be reversed.
  • the features of the present disclosure are applied to a seventh-order low pass filter.
  • FIG. 19 is an equivalent circuit diagram of a filter device 100 G according to a third embodiment.
  • a resonator RC 2 configured similarly to the resonator RC 1 , a capacitor C 45 for adjusting the level of spurious, and a shunt capacitor C 3 are added to the filter device 100 C according to the second embodiment illustrated in FIG. 11 .
  • the resonator RC 2 is connected between the terminal N 2 of the resonator RC 1 and the inductor L 31 .
  • the resonator RC 2 includes inductors L 41 and L 42 and capacitors C 41 to C 43 .
  • the inductors L 41 and L 42 connected in series are connected between a terminal N 3 (third terminal) connected to the terminal N 2 of the resonator RC 1 and a terminal N 4 (fourth terminal) connected to the inductor L 31 .
  • One end of the capacitor C 41 is connected to the terminal N 3 , and the other end thereof is connected to one end of the capacitor C 42 .
  • the other end of the capacitor C 42 is connected to the terminal N 4 . That is, the capacitors C 41 and C 42 connected in series are connected in parallel with the inductors L 41 and L 42 connected in series.
  • the capacitor C 43 for adjusting the frequency of spurious is connected between a connection node N 31 between the inductor L 41 and the inductor L 42 and a connection node N 32 between the capacitor C 41 and the capacitor C 42 .
  • the capacitor C 45 for adjusting the level of spurious is connected between the connection node N 31 between the inductor L 41 and the inductor L 42 and the ground terminal GND. Further, the capacitor C 3 is connected between the terminal N 4 and the ground terminal GND.
  • the filter device 100 G constitutes a seventh-order low pass filter.
  • the capacitors C 43 and C 45 it is possible to reduce the frequency and the level of spurious generated by the inductors of the resonator RC 2 , which improves the attenuation characteristics of the low pass filter.
  • FIG. 20 illustrates filter characteristics of the filter device 100 G according to the third embodiment.
  • the horizontal axis indicates the frequency
  • the vertical axis indicates the insertion loss (solid line LN 40 ) and the return loss (broken line LN 45 ).
  • spurious is generated around 13 GHz between the frequency band BW 1 of microwaves and the frequency band BW 2 of millimeter waves.
  • the attenuation characteristics in the non-pass band of 13 GHz or more are substantially flat with attenuation of 30 dB or more.
  • the frequency and the level of spurious to be generated can be adjusted by disposing a capacitor for frequency adjustment between an intermediate portion of the inductors and an intermediate portion of the capacitors of the LC parallel resonator and disposing a shunt capacitor for the capacitor for frequency adjustment, thereby preventing or reducing a deterioration in attenuation characteristics of the low pass filter.
  • the portion of the capacitors C 43 and C 45 may be replaced with an LC series resonator as in FIG. 9 .
  • a capacitor or an LC series resonator may be disposed between the connection node N 32 between the capacitor C 41 and the capacitor C 42 and the ground terminal GND, as in FIG. 16 or 18 .
  • the “resonator RC 2 ” according to the third embodiment corresponds to the “second resonator” according to the present disclosure.
  • the “capacitor C 3 ”, “capacitor C 41 ”, “capacitor C 42 ”, and “capacitor C 43 ” according to the third embodiment correspond to the “eighth to eleventh capacitors”, respectively, according to the present disclosure.
  • the “inductor L 41 ” and “inductor L 42 ” according to the third embodiment correspond to the “fifth inductor” and “sixth inductor”, respectively, according to the present disclosure.
  • the filter device is a low pass filter.
  • the features of the present disclosure are applied to a third-order or higher-order band pass filter in which an LC parallel resonator is used.
  • FIG. 21 is an equivalent circuit diagram of a filter device 100 H according to a fourth embodiment.
  • the capacitors C 1 and C 2 in the filter device 100 B as a third-order low pass filter illustrated in FIG. 10 have been replaced with resonators RC 3 and RC 4 , respectively.
  • the resonator RC 3 includes an inductor L 51 and a capacitor C 51 connected in parallel between the terminal N 1 of the resonator RC 1 and the ground terminal GND.
  • the resonator RC 4 includes an inductor L 52 and a capacitor C 52 connected in parallel between the terminal N 2 of the resonator RC 1 and the ground terminal GND. That is, the resonators RC 3 and RC 4 constitute an LC parallel resonator, and the filter device 100 H functions as a third-order band pass filter.
  • FIG. 22 illustrates filter characteristics of the filter device 100 H according to the fourth embodiment.
  • FIG. 22 indicates not only the insertion loss (solid line LN 50 ) and the return loss (solid line LN 55 ) for the filter device 100 H, but also the insertion loss (broken line LN 51 ) and the return loss (broken line LN 56 ) for a comparative example in which the capacitor C 23 has been removed from the configuration in FIG. 21 .
  • spurious generated around 31 GHz in the frequency band BW 2 of millimeter waves in the configuration of the comparative example is moved to around 8 GHz in the filter device 100 H. Consequently, the effect on the frequency band BW 2 of millimeter waves is reduced.
  • the frequency of spurious generated by the inductor of the resonator RC 1 can be adjusted to a frequency that does not affect the pass band of another signal by the capacitor C 23 included in the resonator RC 1 .
  • a deterioration in attenuation characteristics of the band pass filter can be prevented or reduced.
  • the “resonator RC 3 ” and “resonator RC 4 ” according to the fourth embodiment correspond to the “third resonator” and “fourth resonator”, respectively, according to the present disclosure.
  • the “inductor L 51 ” and “inductor L 52 ” according to the fourth embodiment correspond to the “seventh inductor” and “eighth inductor”, respectively, according to the present disclosure.
  • the “capacitor C 51 ” and “capacitor C 52 ” according to the fourth embodiment correspond to the “twelfth capacitor” and “thirteenth capacitor”, respectively, according to the present disclosure.
  • an LC series resonator for adjusting the level of spurious is further added to the filter device 100 H according to the fourth embodiment.
  • FIG. 23 is an equivalent circuit diagram of a filter device 100 I according to a sixth modification.
  • an LC series resonator constituted by the inductor L 25 and the capacitor C 25 is disposed between the first connection node N 11 between the inductor L 21 and the inductor L 22 in the resonator RC 1 and the ground terminal GND.
  • FIG. 24 illustrates filter characteristics of the filter device 100 I according to the sixth modification.
  • FIG. 24 indicates the insertion loss (solid line LN 60 ) and the return loss (broken line LN 65 ) for the filter device 100 I.
  • the frequency and the level of spurious generated by the inductor included in the filter device can be adjusted by connecting a shunt capacitor to the capacitor for adjusting the frequency of spurious.
  • An aspect provides a filter device including an input terminal, an output terminal, and a first resonator connected to the input terminal and the output terminal.
  • the first resonator includes a first terminal connected to the input terminal, a second terminal connected to the output terminal, first and second inductors, and first to third capacitors.
  • One end of the first inductor is connected to the first terminal.
  • One end of the second inductor is connected to the second terminal, and the other end thereof is connected to the other end of the first inductor.
  • One end of the first capacitor is connected to the first terminal.
  • One end of the second capacitor is connected to the second terminal, and the other end thereof is connected to the other end of the first capacitor.
  • the third capacitor is connected between the other end of the first inductor and the other end of the first capacitor.
  • the filter device according to any one of (1) to (4), further including a ground terminal, a fifth capacitor connected between the first terminal and the ground terminal, and a sixth capacitor connected between the second terminal and the ground terminal.
  • the filter device uses a first frequency band as a pass band, and uses, as a non-pass band, a frequency band that is higher than the first frequency band.
  • the third capacitor generates spurious in a frequency band between a second frequency band included in the non-pass band and the first frequency band.
  • the filter device further including a third inductor connected between the input terminal and the first terminal, a seventh capacitor connected in parallel with the third inductor, and a fourth inductor connected between the output terminal and the second terminal.
  • the filter device further including a second resonator connected between the second terminal and the fourth inductor, and an eighth capacitor connected between a connection node between the second resonator and the fourth inductor and the ground terminal.
  • the second resonator includes a third terminal connected to the second terminal, a fourth terminal connected to the fourth inductor, fifth and sixth inductors, and ninth to eleventh capacitors.
  • One end of the fifth inductor is connected to the third terminal.
  • One end of the sixth inductor is connected to the fourth inductor, and the other end thereof is connected to the other end of the fifth inductor.
  • One end of the ninth capacitor is connected to the third terminal.
  • One end of the tenth capacitor is connected to the fourth inductor, and the other end thereof is connected to the other end of the fifth capacitor.
  • the eleventh capacitor is connected between the other end of the fifth inductor and the other end of the ninth capacitor.
  • the filter device according to any one of (1) to (4), further including a ground terminal, a third resonator connected between the first terminal and the ground terminal, and a fourth resonator connected between the second terminal and the ground terminal.
  • the third resonator includes a seventh inductor connected between the first terminal and the ground terminal, and a twelfth capacitor connected in parallel with the seventh inductor.
  • the fourth resonator includes an eighth inductor connected between the second terminal and the ground terminal, and a thirteenth capacitor connected in parallel with the eighth inductor.
  • An aspect provides a filter device including a multilayer body in which a plurality of dielectrics are stacked, an input terminal, an output terminal, a ground terminal, first and second paths, and first to fourth capacitor electrodes.
  • the first path is connected to the input terminal.
  • the second path is connected to the output terminal.
  • the first capacitor electrode is connected to the first path.
  • the second capacitor electrode is connected to the second path.
  • the third capacitor electrode is connected to the first and second paths.
  • the filter device in which the first capacitor electrode and the second capacitor electrode are disposed in an identical dielectric layer.
  • the fourth capacitor electrode is disposed in a dielectric layer between the dielectric layer in which the first capacitor electrode and the second capacitor electrode are disposed and a dielectric layer in which the third capacitor electrode is disposed.
  • the filter device according to (10) or (11), further including a ground electrode connected to the ground terminal, and a fifth capacitor electrode and a sixth capacitor electrode that are connected to the third capacitor electrode.
  • a ground electrode connected to the ground terminal
  • a fifth capacitor electrode and a sixth capacitor electrode that are connected to the third capacitor electrode.

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US19/332,135 2023-03-20 2025-09-18 Filter device and method for controlling a filter device Pending US20260019058A1 (en)

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